1. Field of the Invention
The invention relates generally to optical systems for large screen, video projectors. More specifically, the invention pertains to a full color illumination system for a video projector, in which a single light valve including a plurality of primary color, sub-pixel reflectors, effects the selective illumination of full color pixels on a projector screen.
2. Description of the Prior Art
Existing optical systems for light valve type video projectors typically use a single light source, such as an arc lamp, to provide illumination for the projection screen. The output of the light source is first subjected to color separation, so that individual red, green, and blue beams are produced. The separated color beams are then directed to respective light valves, and the resultant illumination from each of the three light valves is recombined for projection upon a screen. The optics used to accomplish the color separation, the information modulation of each color beam by the plural light valves, and the recombination of the three beams can be complex and expensive to implement. Moreover, owing to the additional components required for multiple light valve systems, they remain inefficient, in terms of the intensity of the light transmitted through the system and ultimately projected onto the screen.
Consequently, the need exists for an optical illumination system which is simple, yet efficient, in producing a full color image for a video projection system.
The need also exists for an optical illumination system which uses only a single light valve to control the three primary color beams used in a video projection system.
The need also exists for a single light valve optical system which is inexpensive to manufacture, yet provides luminance and image quality comparable to that provided by more expensive three light valve systems.